1. Field of the Invention
This application relates to power grid management. More particularly, this application relates to an arrangement for power grid monitoring.
2. Description of the Related Art
Electric power systems, for quite some time, have been exposed to delivery patterns for which the transmission and distribution (T&D) equipment was not designed. This is basically a result of a combination of reasons such as adding many non-utility-owned generators at various locations throughout the existing power grid, incorporating intermittent renewable energy resources of various technologies, servicing non-traditional types of loads (electronics, modern control systems, data centers, high-tech manufacturing equipment, plug-in electric vehicles etc. . . . ) as well as the consequent needs for economic power transfers across wide areas instead of only the limited areas for which the T&D equipment was designed.
Moreover, today's operating and planning practices do not rely on adaptation of available resources as system conditions vary. Instead, the worst-case preventive off-line simulations and studies are the basis for how the resources are used as a whole. This approach generally results in hard-to-ensure security as conditions vary significantly outside of the regions for which the system was designed, and, as rule, to under-utilization of resources.
In addition, firm point-to-point bilateral energy contracts superposed on top of coordinated least-cost generation dispatch by the system operators have created hard-to-track parallel flows within and between once loosely coupled control areas. Most recently, the trend to deploy unconventional intermittent resources and connect them to the electric power grid is likely to even further change the T&D power flow patterns once well understood by the system operators.
The overall complexity is likely to increase to the point of being hard to manage using today's industry practices. The complexity is further increased by much faster and larger fluctuations of power injections from their forecasted schedules than with conventional generation resulting in hard-to-predict variations in system operating conditions, as these new resources create qualitatively different transmission interface (flow gate) and line flow patterns.
Furthermore, grid system complexity is increased by the installation and utilization of modern generation and T&D control devices, which aim to substantially improve the power system performance. However, they need proper control decisions and actions in order to achieve such a goal. If this is not the case, such devices are underutilized in the power grid. There exists an entire range of controllers available for typical modern electric power systems but they are not currently coordinated in a systematic way to accommodate broader ranges of operating conditions more efficiently and without endangering system security in the existing prior art systems.
Such controls may include (1) governors of power plants, Automatic Voltage Regulators (AVRs) and Power Systems Stabilizers (PSSs) on power plants, capable of controlling power generated, and terminal voltage, respectively; (2) a variety of mechanically-controllable T&D equipment, such as On-Load Tap Changing Transformers (OLTCs), Shunt Capacitor Banks (ShCBs), Series Capacitor Banks (SCBs) and Phase Angle Regulators (PARs), capable of controlling voltage at the sending or receiving lines, voltages at the buses to which they are connected, and flows through the transmission lines to which they are connected, respectively. More recently, new power-electronically controllable versions of these devices, known as modern flexible AC transmission systems (FACTS) devices, capable of controlling separately or simultaneously voltages and line flows at specific system locations have become an option as well. Such devices are promising because of their ability to avoid wear-and-tear of the basic equipment being controlled by avoiding mechanical stress of concern when using traditional ShCB, SCB, PARs. They are also capable of implementing much faster adjustments to their controlled set points as these are changed. For example, when properly tuned these devices could avoid the danger of creating fast instabilities as the set points of the controllable equipment are being adapted to the changing operating conditions.
Turning back to the operating protocols for such equipment used when managing a power grid, many previously defined prior art protocols for operating the system reliably during both normal and contingency conditions have problems finding a feasible operating point or result in operating conditions that prevent the most efficient and cleanest utilization of the existing generating resources due to reliability-related constraints. Under different situations such operating conditions might not be optimal, which could be further improved by proper utilization and arrangement of existing T&D equipment, which never the less, in current systems, is not fully utilized due to insufficient control decisions resulting from reduced situational awareness or reduced knowledge of control algorithms for optimally operating such equipment.